The present invention relates to clamshell containers in general, and more particularly to molded plastic containers with tamper-resistant features.
Many food items are displayed to customers in transparent plastic clamshell containers. These containers are often filled and often sealed by hand and may contain fresh food such as bakery or prepared fruit and vegetable servings. These pre-filled containers may then be placed in retail areas for direct examination and selection by the customer. Because these food products are not under the direct supervision of store personnel at all times, customers may be concerned that the contents of the containers have not been adulterated, diminished, or otherwise tampered with. Although access to the container contents can be absolutely restricted by a permanent seal, such as by ultrasonic or heat sealing, such an approach has the downside of requiring costly equipment to effectuate, and may be inconvenient for the customer to access after the purchase has been made. Tamper-evident containers have been developed which do not foreclose access to the container contents, but which do give ready evidence that tampering has taken place. If the container bears indications in its appearance that the package has been opened after its initial stocking with goods, a customer may choose to pass that container by, and select one that has no indication of being tampered with.
One approach to providing this evidence is the clamshell container with a lid which is connected by an integral hinge to a base. The lid has a perimeter structure which secures in a press fit to a mating base sealing structure. The lid has a narrow flange which overlies a base flange, and which is too narrow to readily be gripped and displaced by a user. In order to open such a container, the user grips a protruding tab extending from the lid in the region of the hinge, and pulls up in order to sever the lid from the base along a region of weakened material such as a perforation between the lid and the base. The fact that the connection between the base and the lid is not intact gives indication to the attentive would-be purchaser that the container has been compromised. However, there are maneuvers a tamperer can use to release the lid from the base without severing the lid from the base. For example, if the sides of the container are gripped in the opposed hands of a tamperer and rotated in opposite directions, the projecting member of the lid can be distorted to pull away from the base, thereby breaking the resilient seal between the base and the lid. Moreover, if downward pressure is applied to the lid close to the peripheral seal with the base, the lid can be distorted downwardly and made to pull away from the base perimeter, again, largely defeating the package tamper-evident features.
What is needed is a container which can be securely yet releasably closed in such a fashion that tampering with the container to destroy the integrity of the initial filling of the container is made evident.